This invention relates generally to valves, and in particular to ball valves used as sea cocks which provide a flush surface with the ship hull or barrier wall when in the closed position.
The prior art valve used as sea cocks in most cases did not effect a flush seal with the bottom of the boat or hull surface. Instead, the prior art valves were usually mounted a short distance into the interior of the boat with a pipe connection to a through-hull fitting. Such a configuration leads to additional drag on the boat hull due to the cylindrical indention in the hull created by the through fitting, a disadvantage in racing sail boats. A further disadvantage results because the opening in the hull to the sea valve is susceptable to fouling from marine growth and corrosion. In addition, any leak in the through-fitting is not abated by operation of the sea valve.
The prior art sea valves which do provide a closure which is flush with the hull surface generally operate on a principle analogous to a piston. The valve member is usually a disc-shaped plug. Even though a flush seal is created, the sealing surfaces are generally exposed to the sea water when the valve is open thus exposing them to fouling and corrosion. These prior art valves also tend to be large, weigh more and extend some distance into the boat thus requiring more clearance. Because they are large and somewhat more complex to manufacture, they are, of course, more expensive. Also, since the plug is moved into and out of position by a stem that must pass though the valve body, additional seals are required, and these seals are of the sliding type which are not usually as reliable as the simple rotating stem seals used with ball valves. In addition, the flow of fluid through the valve is not in a straight line thus increasing the turbulence of the fluid through the valve resulting in a decrease in the rate of fluid flow for a given valve bore diameter. Because the prior art valves operated in a manner not typical of commonly known valves, the user had to stop to find out what to do to open or close the valve. Such delay might be disastrous in an emergency situation.
Although the sea valve of the present invention is described for use in a ship's hull, it can also be used for other purposes such as a drain valve for tanks in order to eliminate impurities in the initial flow of fluid when the valve is first opened. For example, tanks containing slurries will tend to clog the valves of the prior art which have a space between the valve face and the ball member. The slurries tend to collect in this space and either clog the valve or cause impurities to deposit in this space. By using the valve of the present invention, there is no place for such material to collect. Also, in situations where a tee connection is made to a pipe, the valve of the present invention will not form any cavities to cause turbulences in the fluid flowing in the pipe. Where the pipe contains corrosive material, the valve of the present invention is particularly advantageous since it prevents turbulences which tend to cause excessive corrosion of the pipe downstream from the valve.